Circuit breaker



May 9, 1950 R, L, BRQWN '2,506,991

CIRCUIT BREAKER Fiid April 1, 1946 jfl?. :2 zwem 9mm, an@ s .sfu/fz '1070,95 4

INV ENTOR HUBER L. H/N

`ATTORN EY Patented May 9, 1950 CIRCUIT BREAKER Robert Lowell Brown, Teaneck, N. Bendix Aviation Corporation,

J., assigner to Teterboro, N. J.,

a corporation of Delaware Application April l, 1946, Serial No. 658,804

2 Claims. l

The present application relates to circuit breakers and more particularly to a novel contact and shield arrangement for minimizing and confining the arc resulting upon opening the contacts of a circuit breaker.

It is an object of the invention to provide a contact arrangement for preventing destructive arcing effects at relatively high D. C. voltages in a restricted space and at high altitudes.

Another object of the invention is to provide a 'novel shielded arc chamber formed of an insulating arc resistant material to prevent flashover of the arc to portions of the circuit breaker other than the contacts and including novel means for effecting the lengthening of the arc sufficient to extinguish it.

Another object of the invention is to provide a shielded arc chamber including wall portions to prevent the arc from transferring to portions of the contact switch arm or back-up plate or to portions of the actuating solenoid or conductors and including a conical shaped vent and suitable magnetic arc blow-out arrangement to allow the arc to be lengthened sufficiently to cause its extinction without danger of its transferring to undesired portions of the circuit breaker.

These and other objects and features of the invention are pointed out in the following description in terms of the embodiment thereof which is shown in the accompanying drawings. It is to be understood, however, that the drawings are for the purpose of illustration only, and are not designed as a definition of the limits of the invention, reference being had to the appended claims for this purpose.

In the drawings:

Figure 1 is a sectional view of a circuit breaker embodying the invention.

Figure 2 is a side view of a pair of the novel contacts and illustrating the compound construction of the same.

Figure 3 is a perspective view of one of the shielded contact chambers shown in Figure 1.

Figure 4 is a sectional view taken along the lines 4-4 of Figure 1 and looking in the direction of the arrows.

Referring to the drawings, numeral I indicates a circuit breaker including a movable switch arm 2 operated by suitable means such as the rod 3 actuated by a solenoid or other convenient means not shown.

The arm 2, carries contacts of compound construction and indicated generally by numeral 4. The compound contacts 4 are mounted at opposite ends of the arm 2 and are arranged to mate with similar contacts 5.

Each of the contacts 4 and 5 includes a centrai or main portion 6 of high conductivity material such as silver or other suitable material and aligned with the portion 8 and positioned at opposite ends thereof are end or auxiliary portions 'I formed of carbon or other suitable arc resistant electrical conducting material. The portions E and I of the compound contacts are mounted on suitable electrical conducting bars 8.

The compound contacts 4 are electrically con nected to the movable switch arm 2 through the conducting bars l. The compound contacts 5 are mounted in an arc shield indicated generally by the numeral 9 and formed of a suitable arc resistant electrical insulation material such as porcelain or an asbestos concrete mixture. Suitable electrical connections not shown lead to the compound contacts 5 through the bar 8 thereof.

The shield 9 forms an arc chamber indicated by the numeral Ill and in which the compound contact 5 is positioned. The walls of the arc chamber are arranged so as to t tightly around the compound contact 5. The arc chamber has a barrier or cut out recessed wall portion II of a lower level than the top of the compound contact 4 so as to permit movement of the switch arm 2 and contact 4 into contacting relation with the compound contact 5, but the barrier IIy extends suillciently above the top of compound contact 5 to prevent the arc resulting upon the opening of contact 5 from transferring to undesired portions.

A permanent magnet I2 is mounted in the arc shield 9 and has opposite poles I3 and I4 positioned substantially at a ninety degree angle to the aligned portions 6 and 1 of the contact 5 so that the magnetic field of the magnet is so oriented with respect to the compound contacts 5 that upon the compound contact 4 opening the contact 5 the resultant arc is blown outward by the magnetic field onto one or the other of the carbon or arc resistant portions 1, depending upon the direction of current iiow. Thus the burning or destructive effect of the arc will be conilned by the wall portions of the arc shield 9 and minimized at the arc resistant portions 1.

In order, however, to allow the resulting arc to be lengthened sumciently to cause its extinction, conical shaped vents I5 extend through the wall portion of the shield 9. Each of the The barrier -ll and Wall of the shield 9 surroundin'g the arc chamber I0, together with the conical shaped vents I in the wall of the shield 9 and magnetic blow out arrangement I2 causes the lengthening of the arc sufficiently to eiect its extinction, while confining the arc so that it may not transfer to undesired portions of the circuit breaker.

It will be readily seen from the foregoing explanation that there has been thus provided a novel and simple shielded compound contact magnetic blow out arrangement for a circuit breaker which is effective to prevent iiash-over of arc at high altitudes and within restricted space.

What is claimed is: 1. In a device of the character described, the

combination, comprising, a pair of separable contact members, a magnet having poles positioned at opposite sides of the contact members, each of said members including a main portion formed of silver having a high electrical `conductivity land an auxiliary portion posi- .tioned at opposite ends of the main portion and formed of anarc-resistant electrical conductive carbon, the main portion of each of said contact members protruding above the surface of the auxiliary portion so that conduction when the contact members are closed is between the main portions of each of said contact members,

and the magnet being effective upon the separation ofsaid contact members to blow a resulting arc onto the auxiliary portion for minimizing the effect of the arc on the main portion, a switch arm for moving one of said contact mem- 'bers relative to the other, and a shield formed of an arc-resistant porcelain insulating material, said shield having a wall portion surrounding said contact members so as to form a chamber within which said Contact members are positioned, the wall portion of said shield having a recess for permitting movement of the switch arm and the one contact member relative to the other contact member, and the Wall portion of said shield having conical vents formed therein which open from said chamber, said conical vents extending at an acute angle from immediately adjacent said auxiliary portions oi' said contact members to the exterior, said conical vents having an inner open end of greater diameter than the outer open end and arranged so as to permit lengthening of the arcfrom the auxiliary portions to the exterior for effecting extinction thereof.

2. In a magnetic blow-out device of the type `including a pair of! separable contacts, a blowout magnet, each of said contacts including at least two portions, a i'lrst portion formed of a material having a relatively high electrical conductivity and a second portion formed of an electrical conducting material having greater arc resistant properties than said iirst portion, said first and second portions extending in alignment at a substantially ninety-degree angle to the magnetic iield of said blow-out magnet so that upon separation of said contacts a resulting arc is blown onto the second portions of said contacts, a shield formed of an arc-resistant electrical insulating material, and said shield having a wall portion surrounding said contacts so as to form a chamber within which said contacts are positioned; said arrangement being particularly characterized by the rst portion of each contact protruding suiciently above the surface of the second more arc-resistant portion of the contact as to assure that all contact closing pressure is applied to the iirst portions of said contacts, and the wall portion of said shield having a vent formed therein extending at an acute angle from the second portions of said contacts and opening from said chamber to the exterior for permitting further lengthening of the arc from the second portions to the exterior so as to eiect extinction thereof.

` ROBERT LOWELL BROWN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Healis June 13, 1944 

